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RE: [PATCHv4, MIPS] Add support for O32 FPXX and program header based ABI information
- From: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: "'libc-alpha at sourceware dot org'" <libc-alpha at sourceware dot org>, "Moore, Catherine (Catherine_Moore at mentor dot com)" <Catherine_Moore at mentor dot com>, 'Andrew Pinski' <pinskia at gmail dot com>, "Rich Felker (dalias at libc dot org)" <dalias at libc dot org>, Rich Fuhler <Rich dot Fuhler at imgtec dot com>, "Maciej W. Rozycki (macro at linux-mips dot org)" <macro at linux-mips dot org>
- Date: Tue, 6 Jan 2015 15:13:18 +0000
- Subject: RE: [PATCHv4, MIPS] Add support for O32 FPXX and program header based ABI information
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B0235320F8DFA4 at LEMAIL01 dot le dot imgtec dot org> <alpine dot DEB dot 2 dot 10 dot 1412311718240 dot 26199 at digraph dot polyomino dot org dot uk> <alpine dot DEB dot 2 dot 10 dot 1412312210030 dot 26199 at digraph dot polyomino dot org dot uk>
Here's my first attempt at a news entry for this. I suspect it is too
verbose but covers the kind of things I believe are important.
Thanks,
Matthew
* NEWS: Announce support for new MIPS ABI extensions.
---
NEWS | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/NEWS b/NEWS
index 63918df..d1fa510 100644
--- a/NEWS
+++ b/NEWS
@@ -49,6 +49,26 @@ Version 2.21
* Merged gettext 0.19.3 into the intl subdirectory. This fixes building
with newer versions of bison.
+
+* Support for MIPS o32 FPXX, FP64A and FP64 ABI Extensions.
+ The original MIPS o32 hard-float ABI requires an FPU where double-precision
+ registers overlay two consecutive single-precision registers. MIPS32R2
+ introduced a new FPU mode (FR=1) where double-precision registers extend the
+ corresponding single-precision registers which is incompatible with the
+ o32 hard-float ABI. The MIPS SIMD ASE and the MIPSR6 architecture both
+ require the use of FR=1 making a transition necessary. New o32 ABI
+ extensions enable users to migrate over time from the original o32 ABI
+ through to the updated o32 FP64 ABI. To achieve this the dynamic linker now
+ tracks the ABI of any loaded object and verifies that new objects are
+ compatible. Mode transitions will also be requested as required and
+ unsupportable objects will be rejected. The ABI checks include both soft and
+ hard float ABIs for o32, n32 and n64.
+
+ GCC 5.0 onwards:
+ It is strongly recommended that all o32 system libraries are built using the
+ new o32 FPXX ABI (-mfpxx) to facilitate the transition as this is compatible
+ with the original and all new o32 ABI extensions. Configure a native
+ MIPS GCC compiler using --with-fp-32=xx to set this by default.
Version 2.20
--
2.2.1